Our previous work has indicated that hyaluronate interacts with the surface of various types of cells and that this interaction may affect their behavior during tissue formation and remodelling. Specifically we have proposed that a hyaluronate-rich matrix may be necessary for creating appropriate spaces in the embryo for cell migration and that hyaluronate may interact with the surface of migrating cells in such manner as to inhibit precocious differentiation. We propose to characterize cell surface receptor sites for binding of hyaluronate, to examine changes in these receptors on viral transformation and during morphogenesis, and to test the role of binding of hyaluronate to the cell surface on several aspects of cell behavior. We will also investigate the relationship of cell surface hyaluronate to associated protein and the postsynthetic processing of hyaluronate during secretion. We will attempt to describe in detail the ultrastructural localization of hyaluronate and hyaluronidase during morphogenetic events in vivo. Finally we will extend our preliminary studies of the relationship of hyaluronate to tumor cell invasion using in vivo and in vitro systems. By these investigations we hope to contribute directly to an understanding of the role of hyaluronate in the regulation of normal and aberrant cell behavior.